Seppo
Super Member
I found a High Fidelity review of Infinity RS-5b from April 1985, that includes full specs and measurements:
http://www.audiokarma.org/forums/attachment.php?attachmentid=544063&stc=1&d=1412344177
Now, the interesting part is that the impedance drops down to 2.2 Ohm (I have not seen any reports of actual measured impedance for RS-IIIa/b to RS-6a/b series before finding this review). I am very surprised by this, since I expected this mid-tier RS series of speakers to be a bit more easier impedance/load wise (being rated by Infinity 4-8 Ohms). But this number is quite low, not as low as with Kappa 8's or 9's, but still.
The key paragraph is as follows:
"...Sensitivity [88 dB SPL] is about par for a contemporary speaker, and the average impedance [11.7 Ohms] is moderately high. The impedance curve is quite irregular, however, with values ranging from a maximum of 29 Ohms at 530 Hz to a low of 2.2 Ohms at 1.8 kHz with the driver level controls centered. Turning the midrange control all the way down raises the minimum to only 2.7 Ohms, and turning it all the way up drops the impedance to 1.6 Ohms. Poorly designed amplifiers may respond badly to this load, and we would counsel against running a pair of RS-5bs in parallel with another set of speakers..."
As I have been saying before on this forum, my Onkyo A-9070 with 140 wpc at 4 Ohms (75 wpc at 8 Ohms) sounds great with its AWRAT high current tech, and seems to be a good match for this line of Infinity RS speakers (I have RS-IIIa's).
http://www.audiokarma.org/forums/attachment.php?attachmentid=544063&stc=1&d=1412344177
Now, the interesting part is that the impedance drops down to 2.2 Ohm (I have not seen any reports of actual measured impedance for RS-IIIa/b to RS-6a/b series before finding this review). I am very surprised by this, since I expected this mid-tier RS series of speakers to be a bit more easier impedance/load wise (being rated by Infinity 4-8 Ohms). But this number is quite low, not as low as with Kappa 8's or 9's, but still.
The key paragraph is as follows:
"...Sensitivity [88 dB SPL] is about par for a contemporary speaker, and the average impedance [11.7 Ohms] is moderately high. The impedance curve is quite irregular, however, with values ranging from a maximum of 29 Ohms at 530 Hz to a low of 2.2 Ohms at 1.8 kHz with the driver level controls centered. Turning the midrange control all the way down raises the minimum to only 2.7 Ohms, and turning it all the way up drops the impedance to 1.6 Ohms. Poorly designed amplifiers may respond badly to this load, and we would counsel against running a pair of RS-5bs in parallel with another set of speakers..."
As I have been saying before on this forum, my Onkyo A-9070 with 140 wpc at 4 Ohms (75 wpc at 8 Ohms) sounds great with its AWRAT high current tech, and seems to be a good match for this line of Infinity RS speakers (I have RS-IIIa's).
